The structural, rotational, and vibrational properties of BnNn+ clusters (n = 3-10) have been investigated using density functional theory (DFT) and compared with that of their neutral counterparts. The BnNn+ species with n = 4, 6, 8, 10 are found to possess as lowest energy form a fully regular structure of D-nh symmetry, as the neutral species. In both cases, their IR vibrational spectrum invariably contains four Lines, relating to one out-of-plane nondegenerate and three in-plane doubly degenerate normal modes. On the other hand, the BnNn clusters with n = 3, 5, 7, 9 are found to evolve from a fully regular D-nh structure to a more alternating one upon an adiabatic ionization process. In this case, ionization is also shown to strongly enhance the infrared activity. Rotational moments and adiabatic ionization potentials are eventually provided to trace the structural variations induced by ionizing these clusters.